Snapshot Administration Guide for Hitachi NAS Platform

Part Number

For users whose data availability cannot be disrupted by management functions such as system backup and data recovery, snapshots create near-instantaneous, read-only images of an entire file system at a specific point in time. Snapshots allow users to easily restore lost files without having to retrieve the data from backup media, such as tape.

Snapshots capture a moment in time for a live file system. They don't consume any disk space when they are created. However, over time, the space occupied by a snapshot grows, as the live file system continues to change.

Snapshots solve the problem of maintaining consistency within a backup; specifically, during a system backup, users continue to modify its component files, resulting in backup copies that may not provide a consistent set. Since a snapshot provides a frozen image of the file system, a backup copy of a snapshot (rather than of the live file system) provides a usable, consistent backup that appears to a network user like a directory tree. Users with appropriate access rights can retrieve the files and directories that it contains through SMB, NFS, FTP, or NDMP.

Note: Snapshots alone should not be considered a backup solution, as they do not provide a second copy of data in a different location.